THEME 5.0: AGRICULTURE AND ENVIRONMENTAL MANAGEMENT
Environmental degradation
Environmental degradation refers to the deterioration of the environment through the depletion of resources such as air, water, and soil; the destruction of ecosystems; and the extinction of wildlife. It is defined as any change or disturbance to the environment perceived to be harmful or undesirable. According to the I=PAT equation, environmental impact (I) or degradation results from the combination of a large and growing human population (P), increasing economic growth or per capita affluence (A), and the use of resource-depleting and polluting technology (T).
Environmental degradation is recognized as one of the ten major threats by the United Nations High-level Panel on Threats, Challenges, and Change. The United Nations International Strategy for Disaster Reduction defines environmental degradation as “the reduction of the capacity of the environment to meet social and ecological objectives and needs.” It manifests in many forms, including the destruction of natural habitats and depletion of natural resources. Efforts to combat environmental degradation include environmental protection and resource management strategies.
Water degradation
A major component of environmental degradation is the depletion of fresh water resources on Earth. Only about 2.5% of all water on Earth is fresh water, with the remainder being salt water. Of this fresh water, 69% is frozen in ice caps in Antarctica and Greenland, leaving only about 30% of the 2.5% available for consumption. Fresh water is vital for life on Earth, as it transports nutrients and chemicals within the biosphere, sustains plants and animals, and shapes the Earth’s surface through transportation and deposition of materials.
The top three uses of fresh water account for 95% of its consumption: approximately 85% is used for irrigation of farmland, golf courses, and parks; 6% is used for domestic purposes such as indoor bathing and outdoor gardening; and 4% is used for industrial purposes including processing, washing, and cooling in manufacturing. It is estimated that one in three people worldwide already face water shortages. Nearly one-fifth of the global population lives in areas of physical water scarcity, and almost one-quarter live in developing countries lacking the infrastructure to access water from rivers and aquifers. Water scarcity is expected to worsen due to population growth, urbanization, rising living standards, and climate change.
Climate change and temperature
Climate change significantly affects the Earth’s water supply in numerous ways. It is predicted that the mean global temperature will rise in the coming years, accompanied by an increase in atmospheric CO2. Both factors influence water resources, as evaporation depends strongly on temperature and moisture availability, which affects groundwater replenishment.
Transpiration from plants may be altered by increased atmospheric CO2, potentially decreasing water use but also possibly increasing it due to larger leaf areas. Rising temperatures can shorten the snow season and intensify snowmelt, causing earlier peak runoff, which impacts soil moisture, flood and drought risks, and water storage capacity depending on the region.
Warmer winters reduce snowpack, diminishing summer water resources, especially in mid-latitude and mountainous regions reliant on glacial runoff. Initially, higher temperatures cause rapid glacier melt in summer, but over time glaciers retreat, reducing meltwater and water supply annually.
Thermal expansion of water and increased glacier melt contribute to sea-level rise, which threatens freshwater supplies in coastal areas. Saltwater intrusion into river mouths and deltas increases salinity in reservoirs and aquifers. Groundwater depletion linked to climate change also contributes to sea-level rise, creating a feedback loop that exacerbates freshwater supply problems.
Rising air temperatures also increase water temperatures, making water more susceptible to bacterial growth. This affects aquatic ecosystems by altering species’ temperature sensitivities and reducing dissolved oxygen levels, which impairs water bodies’ self-purification processes.
Causes of Environmental Degradation
The primary cause of environmental degradation is human disturbance. The extent of environmental impact varies depending on the cause, habitat, and the plants and animals inhabiting it.
Habitat Fragmentation
Habitat fragmentation has long-term environmental impacts, potentially destroying entire ecosystems. An ecosystem includes all living and non-living components within a unit, such as plants, animals, streams, lakes, and soils.
Fragmentation occurs when development breaks up continuous stretches of land, such as roads cutting through forests or trails winding through prairies. Although it may seem minor, fragmentation has serious consequences, especially for specialized plant and animal communities that require large areas to maintain healthy genetic diversity.
Area Sensitive Animals
Some wildlife species need large areas to fulfill their needs for food, habitat, and other resources. These are called area-sensitive species. When habitats are fragmented, large patches no longer exist, making it difficult for these animals to survive. This can lead to their becoming threatened or endangered, which disrupts the food web and harms the environment.
Aggressive Plant Life
Habitat fragmentation often leads to land disturbance, allowing opportunistic and invasive plant species such as garlic mustard and purple loosestrife to establish themselves. These aggressive plants can dominate an environment, displacing native flora and reducing food resources for wildlife. Entire ecosystems may be threatened with extinction as a result.
Some invasive weeds are so destructive that they are legally declared noxious by federal or state governments to prevent their spread. The cultivation and sale of noxious weeds are prohibited by law to protect unspoiled areas.
Human Sources of Environmental Deterioration
Human activities are a major source of environmental degradation.
Water and Air Pollution
Water and air pollution are common causes of environmental degradation. Pollution introduces harmful contaminants that can injure or kill plants and animals. These two types of pollution often occur together and compound environmental harm.
Acid Rain
Acid rain forms when sulfur dioxide emissions from coal plants combine with moisture in the air, creating acid precipitation. Acid rain acidifies lakes, streams, and soils, harming aquatic life and vegetation. According to the U.S. Environmental Protection Agency (EPA), excessive acid rain can make environments inhospitable to life, causing plants and animals to die and leading to environmental deterioration.
Agricultural Runoff
Agricultural runoff is a significant source of pollutants that degrade environments. The EPA identifies agriculture as the primary source of water pollution. Surface water runoff carries fertilizers and pesticides from farmland into lakes and streams, introducing harmful substances into waterways.
Fertilizers, whether organic or synthetic, pose risks. Those high in phosphorus can cause algal blooms in lakes. When algae die, bacteria decompose the organic matter, consuming dissolved oxygen and creating hypoxic conditions. This leads to the death of plants, fish, and other organisms, turning lakes into “dead zones” where life cannot be sustained.
Urban Development
Urban development is a major cause of environmental degradation. As populations grow, more land is needed for housing and agriculture. Wetlands have been drained, and prairies plowed over. According to the North Carolina State University Water Quality Group, less than 50% of the nation’s wetlands remain. National Geographic reports that only 5% of native prairies still exist.
Environmental degradation is a critical issue. Some damaged environments may never recover, resulting in permanent loss of plants and animals. To reduce future impacts, city planners, industries, and resource managers must consider the long-term environmental effects of development. With careful planning, future degradation can be prevented.
Natural Causes
Environmental degradation can also result from natural causes. While human activities are the most common cause, ecosystems naturally change over time. Some ecosystems degrade to the point where they can no longer support their native life.
Natural disasters such as landslides, earthquakes, tsunamis, hurricanes, and wildfires can devastate local plant and animal communities, rendering them unable to function. This destruction can be physical or result from the introduction of invasive species carried by events like hurricanes. When new species invade, the environment may be unable to adapt, leading to degradation.
Causes of Environmental Degradation
Some species require large areas to provide food, living space, and other resources. These are called area-specific species. When habitats are fragmented, large patches disappear, making it harder for wildlife to survive. The environment continues, but without the animals and plants needed to sustain it properly.
- Land Disturbance: Land damage is a fundamental cause of environmental degradation. Many weedy plant species, such as garlic mustard, are invasive. Habitat breaches allow them to spread, displacing native plants. This results in areas dominated by a single plant species that does not support diverse wildlife, threatening entire ecosystems.
- Pollution: Pollution in any form—air, water, land, or noise—is harmful to the environment. Air pollution contaminates the air we breathe, causing health problems. Water pollution degrades drinking water quality. Land pollution damages the Earth’s surface through human activities. Noise pollution can cause irreversible hearing damage from continuous loud sounds like traffic or industrial machinery.
- Overpopulation: Rapid population growth strains natural resources, leading to environmental degradation. Improved medical care has lowered mortality rates and increased lifespan, resulting in higher population. More people require more food, clothing, and shelter, increasing demand for land and causing deforestation, which further degrades the environment.
